Laser machining method

ABSTRACT

A laser welding apparatus (1) includes a laser welding head (5) configured to irradiate a workpiece (10) with laser light, a welding filler feeding mechanism (6) configured to supply a welding material to a position on which laser welding is performed, and a hollow structural moving mechanism (100) configured to move a welding unit (50) including the laser welding head and the welding filler feeding mechanism. The hollow structural moving mechanism has an insertion portion (3a) through which an optical cable (41) of the laser welding head and a wire material (62) of the welding filler feeding mechanism are inserted.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 15/999,780 filed Aug. 20, 2018, which is a National Stage ofInternational Application No. PCT/JP2017/045914 filed Dec. 21, 2017,claiming priority based on Japanese Patent Application No. 2017-071614filed Mar. 31, 2017, the content of which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a laser welding apparatus, a lasermachining apparatus, a laser welding method, a method for manufacturinga bearing, a method for manufacturing a machine, a method formanufacturing a vehicle, a bearing, a machine, and a vehicle, andparticularly, to a technique for performing a laser processing of anarbitrary shape such as an annular shape or an S shape on an object mainbody to be machined.

TECHNICAL BACKGROUND

For example, Patent Document 1 describes an apparatus configured toperform laser welding on a tubular (cylindrical) workpiece when a lasermoves only in a Z direction (vertical direction) by rotating aworkpiece. Patent Document 2 describes an apparatus configured toperform laser welding on a tubular (cylindrical) workpiece when a lasermoves only in an X direction (a horizontal direction which isperpendicular to a vertical direction) by rotating a work.

RELATED ART DOCUMENTS Patent Document

-   Patent Document 1-   Japanese Patent Application, Publication No. 2017-001068-   Patent Document 2-   Japanese Patent Application, Publication No. 2015-226925

SUMMARY OF INVENTION Technical Problem

An object of an aspect of the present invention is to provide a laserwelding apparatus, a laser machining apparatus, a laser welding method,a method for manufacturing a bearing, a method for manufacturing amachine, and a method for manufacturing a vehicle which are appropriatefor miniaturization of an apparatus, are appropriate for a relativelylarge workpiece, and/or are advantageous for handing an optical cableand a material. Another object of an aspect of the present invention isto provide a laser welding apparatus, a laser machining apparatus, alaser welding method, a method for manufacturing a bearing, a method formanufacturing a machine, and a method for manufacturing a vehicle whichcan manufacture a high quality product. Yet another object of an aspectof the present invention is to provide a high-quality bearing, machine,and a vehicle.

Solution to Problem

A laser machining apparatus according to a first aspect of the presentinvention includes: a head having an optical outlet from which laserlight is output; an optical cable attached to the head; a nozzleattached to the head to direct a material supplied to a target; a movingmechanism having a driving portion; and a controller, wherein the movingmechanism includes a first mechanism to allow the head to move in acurved manner in at least a two-dimensional plane and a secondmechanism, which has a rotational axis, to allow the head to rotate 360°or more around the rotational axis along with the optical cable and thematerial, and the controller has an attitude control mode in which themoving mechanism is controlled so that the head rotates around therotational axis while the head moves in the curved manner in at leastthe two-dimensional plane.

A second aspect of the present invention is a laser welding apparatuswhich performs laser welding on a workpiece including: a laser weldinghead configured to irradiate the workpiece with laser light; a weldingfiller feeding mechanism configured to supply a welding material to aposition on which the laser welding is performed; and a hollowstructural moving mechanism configured to move a welding unit includingthe laser welding head and the welding filler feeding mechanism, thehollow structural moving mechanism having an insertion portion throughwhich wire materials of the laser welding head and the welding fillerfeeding mechanism are inserted.

A third aspect of the present invention is a laser welding method usingthe laser welding apparatus in which the hollow structural movingmechanism and a two-dimensional actuator are synchronously driven sothat an irradiation direction of laser light of the laser welding headand a feeding direction of a welding filler of the welding fillerfeeding mechanism are upheld in a predetermined manner with respect to atraveling direction of the laser welding head.

A fourth aspect of the present invention is a laser welding method usingthe laser welding apparatus in which the hollow structural movingmechanism and a three-dimensional actuator are synchronously driven sothat an irradiation direction of laser light of the laser welding headand a feeding direction of a welding filler of the welding fillerfeeding mechanism are upheld in a predetermined manner with respect to atraveling direction of the laser welding head.

A bearing according to a fifth aspect of the present invention has aninner ring, an outer ring, a roller, a pin, a cage ring and a weldedportion in which the pin and the cage ring are welded, and the weldedportion is provided only around the pin.

A bearing according to a sixth aspect of the present invention ismanufactured using the above-described laser machining apparatus or theabove-described laser welding apparatus.

A machine according to a seventh aspect of the present inventionincludes: the above-described bearing.

A vehicle according to an eighth aspect of the present inventionincludes the above-described bearing.

A method for manufacturing a bearing according to a ninth aspect of thepresent invention includes using the above-described laser machiningapparatus or the above-described laser welding apparatus.

A method for manufacturing a machine according to a tenth aspect of thepresent invention includes using the above-described laser machiningapparatus or the above-described laser welding apparatus.

A method for manufacturing a vehicle according to an eleventh aspect ofthe present invention includes using the above-described laser machiningapparatus or the above-described laser welding apparatus.

Advantageous Effects of Invention

According to an aspect of the present invention, it is possible toprovide a laser welding apparatus, a laser machining apparatus, a laserwelding method, a method for manufacturing a bearing, a method formanufacturing a machine, and a method for manufacturing a vehicle whichare appropriate for miniaturization of an apparatus, are appropriate fora relatively large workpiece, and/or are advantageous for handing anoptical cable and a material. Furthermore, according to an aspect of thepresent invention, it is possible to provide a laser welding apparatus,a laser machining apparatus, a laser welding method, a method formanufacturing a bearing, a method for manufacturing a machine, and amethod for manufacturing a vehicle which can manufacture a high qualityproduct. According to an aspect of the present invention, it is possibleto provide a high-quality bearing, machine, and vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram showing a laser machining apparatus(laser welding apparatus) according to an embodiment of the presentinvention.

FIG. 1B is a schematic explanatory view of an XYZ stage in the laserwelding apparatus.

FIG. 2 is a diagram illustrating the movement of a head during laserprocessing.

FIG. 3 is a diagram illustrating the movement of the head during laserprocessing in an attitude control mode.

FIG. 4 is a diagram illustrating the movement of the head during laserprocessing in the attitude control mode.

FIG. 5 is a schematic diagram illustrating a plurality of examples of acavity unit.

FIG. 6 is a schematic diagram illustrating an extra-large size rollerbearing as an example of a target to be machined.

FIG. 7A is a schematic diagram illustrating a welded portion in metalactive gas (MAG) welding.

FIG. 7B is a schematic diagram illustrating a welded portion in laserwelding.

FIG. 8 is a schematic diagram showing a conventional laser weldingapparatus.

DESCRIPTION OF EMBODIMENTS

An embodiment of a laser machining apparatus (laser welding apparatus)according to the present invention will be described below on the basisof the drawings. Note that the present invention is not to beinterpreted to be limited to this embodiment and the design thereof canbe appropriately modified within the scope of the present invention.

In this specification, the laser machining apparatus is an apparatusconfigured to perform a predetermined processing on a target using laserlight and a processing material. In an example, the laser machiningapparatus is a laser welding apparatus configured to supply a filler asa material (wire material, welding material, or filler material) andenergy of laser light and to perform a welding processing on a machiningposition on a target. In the laser welding apparatus, a workpiece isirradiated with laser light as an energy source from an optical outletof a laser head. Part of the workpiece and/or the filler is melted andthen the melted material solidifies. The laser welding apparatus caninclude a hybrid type welding apparatus for laser welding and otherwelding, for example, a laser/arc hybrid welding apparatus obtained bycombining laser welding and arc welding. In another example, the lasermachining apparatus can be applied to an apparatus configured to performprocesses other than a welding processing using laser light and amaterial such as a three-dimensional printing system.

In one embodiment, as illustrated in FIG. 1A, a laser welding apparatus(laser machining apparatus) 1 includes a laser welding head (laser heador head) 5 configured to irradiate a workpiece 10 with laser light(laser beam) 51 and a welding filler feeding mechanism (feeder) 6configured to supply a welding material to a position at which laserwelding is performed. The head 5 includes an optical outlet (outletsurface or distal end element) 5 a through which the laser light 51 isoutput. At least part of the welding filler feeding mechanism 6 isattached to the laser welding head 5. In an example, the head 5 has anoptical cable (laser transmission optical fiber cable) 41 and a nozzle(material guide) 61 attached thereto. The nozzle 61 directs a processingmaterial (filler material) 62 supplied to the target (workpiece) 10. Thefiller 62 is fed through a feeder function of the welding filler feedingmechanism 6 and the filler 62 is pushed out from the distal end (nozzleopening) of the nozzle 61. The nozzle 61 is fixed to the head 5 using abracket (attachment plate) 63. The head 5 can be moved using a movingmechanism (hollow structural moving mechanism) 100 which will bedescribed later. The nozzle 61 supported by the head 5 can be movedtogether with the head 5. The head 5 and the nozzle 61 move integrallywith each other, and accordingly the optical cable 41 and the material(filler material) 62 move. For example, the material 62 can include awire material and a material other than a wire material (powdermaterial, fluid material, or the like).

In the related art, as illustrated in FIG. 8 , in order to perform laserwelding in an annular shape to join a component whose external form iscylindrical to another component, an annular welding path 14 is obtainedby fixing a workpiece 15 to a main rotational shaft 16, rotating theworkpiece 15 (in an arrow symbol L direction), and keeping an attitudeof the laser head 12 fixed. Generally, in order to prevent reflectedlight from a surface of the workpiece 14 from returning directly to anddamaging the laser head 12 in the laser welding apparatus 11, a laserirradiation axis is inclined by a fixed angle (head axis inclinationangle) D1 with respect to a vertical direction of a surface of theworkpiece 15.

In a conventional laser welding apparatus, when annular laser welding isperformed on part of a very large target object to be machined(workpiece), a size of a mechanism for rotating the workpiece is largeand thus a large installation space for the laser welding apparatus isrequired. On the other hand, when annular laser welding is performed ona fixed workpiece by rotatably moving the welding head, interferencebetween, twisting of, or the like a wiring and cables is an obstacle ifit is attempted to rotate a welding head axis to keep the welding headand a feeding direction of the welding filler fixed. Particularly, whenan optical fiber transmission type laser is used, a laser transmissionoptical fiber cable is vulnerable with respect to a physical force andbending. Thus, it is necessary not to apply an excessive force to thelaser transmission optical fiber cable.

Referring again to FIG. 1A, in one embodiment, the laser weldingapparatus (laser machining apparatus) 1 includes the moving mechanism(hollow structural moving mechanism) 100 having a driving portion suchas a motor and a control unit (a controller) 110. The moving mechanism100 has a first mechanism 2 and a second mechanism 3.

The first mechanism 2 guides the head 5 along at least a predeterminedtwo-dimensional plane (for example, an XY plane). The second mechanism 3has a rotational axis W and guides the rotation of the head 5. When thefirst mechanism 2 is used, the head 5 can be moved in a curved manner inat least a two-dimensional plane (for example, an XY plane). When thesecond mechanism 3 is used, the head 5 can rotate 360° or more around arotational axis W along with the optical cable 41 and the material 62.

Examples of a rotatable range include 0° or more and about 360, 390,420, 450, 480, 510, 540, 570, 600, 630, 660, 690, or 720 or less. Theabove-described numerical values are typical examples and the rotatablerange is not limited to the above-described numerical values. Inaddition, the first mechanism 2 can be configured to be able to displacea position of the head 5 in a direction which is orthogonal to atwo-dimensional plane (for example, a position in a Z direction or avertical direction) while moving the head 5 in a two-dimensional plane(for example, an XY plane or a horizontal plane). The first mechanism 2can include a two-dimensional actuator which can move in an X directionand a Y direction (for example, a unit obtained by combining an XY stageand a single-axis actuator). Alternatively, the first mechanism 2 caninclude a three-dimensional actuator which can move in the X direction,the Y direction, and the Z direction (for example, a unit obtained bycombining an XYZ stage and a single-axis actuator). Alternatively, thefirst mechanism 2 can be configured to include an articulated robot. Inan example of a single-axis actuator, the first mechanism 2 can includea carrier unit obtained by integrally combining a ball screw, a linearguide, and a support bearing.

The rotational axis W can be set to be parallel to an axis (for example,the Z axis or a vertical axis) which is orthogonal to a predeterminedtwo-dimensional plane (for example, an XY plane or a horizontal plane).The rotational axis W moves along with the movement of the head 5 usingthe first mechanism 2. In other words, when the head 5 moves in a curvedmanner above a two-dimensional plane, the rotational axis W also movesin a curved manner above the two-dimensional plane in accordance withthe movement of the head 5. In an example, the rotational axis W isdisposed near a rear portion of the head 5 (an end portion on an inputside of the laser light 51 or a side to which the optical cable 41 isattached) rather than a front portion thereof (an end portion on anoutput side of the laser light or the optical outlet 5 a). In anotherexample, the rotational axis W is disposed near a center of the head 5.In yet another example, the rotational axis W is disposed near a frontportion of the head 5 rather than a rear portion of the head 5. Forexample, the rotational axis W may be set to cross a front portion, acentral portion, or a rear portion of a main body of the head 5.Alternatively, the rotational axis W may be set at a position away fromthe main body of the head 5 such that it does not substantially crossthe main body of the head 5.

In an example, the laser welding apparatus (laser machining apparatus) 1includes a head axis tilting mechanism 4 and at least one of the head 5and the nozzle 61 is disposed to be inclined with respect to therotational axis W. For example, a central axis of the head 5 may bearranged to be inclined with respect to the rotational axis W so thatthe laser light 51 is incident on a machining position on the workpiece10 substantially in an inclined manner. The laser light 51 reflectedfrom the workpiece 10 is substantially prevented from being directedtoward the head 5 and thus damage to the head 5 due to the reflectedlight is prevented. For example, a central axis of the nozzle 61 isarranged to be inclined with respect to the rotational axis W so that amaterial (filler material) is fed to a machining position on theworkpiece substantially in an inclined manner. Thus, a material 61 isappropriately set between the workpiece 10 and the head 5. The energy ofthe laser light 51 is appropriately transmitted to the material 61 andthe melted material 61 is appropriately disposed on a welding targetportion Q.

The controller 110 includes a storage device that stores a controlprogram or the like which controls the moving mechanism 100 and aprocessor (processor, processing circuitry, or circuitry) configured toexecute the control program. The controller 110 has an attitude controlmode for controlling the moving mechanism 100 so that the head 5 rotatesaround the rotational axis W while the head 5 is moving in a curvedmanner at least in a two-dimensional plane.

In an example, as illustrated in FIGS. 2 and 3 , in the attitude controlmode, the controller 110 controls the moving mechanism 100 so that alocation of at least one of the optical outlet 5 a of the head 5 and thedistal end of the nozzle 61 is upheld in front of a machining position(welding position) P above a target (forward in a moving direction ofthe head 5) while the head 5 is moving in a curved manner at least in atwo-dimensional plane. For example, during a welding processing, both ofthe optical outlet 5 a of the head 5 and the distal end of the nozzle 61are continuously located in front of the machining position (weldingposition) P above the target (forward in the moving direction of thehead 5).

In an example, as illustrated in FIG. 3 , positions of the opticaloutlet 5 a and the distal end of the nozzle 61 are located at forwardpositions with respect to the machining position P on an extension lineof a straight line portion in a welding target portion (target line) Qin the straight line portion (forward positions in the moving directionof the head 5). Alternatively, the positions may be at forward positionswith respect to the machining position P in a tangential direction of acurved line in a curved portion of the target line Q. Laser light isradiated from the front of the machining position P toward the machiningposition P in the tangential direction in the curved portion of thetarget line Q and a material (filler material) is supplied in thetangential direction. When a constant attitude of the head 5 ismaintained with respect to the machining position P, high quality anduniform welding is performed on the entire welding target portion Q. Inanother example, the head 5 can be set to an attitude different from theabove-described attitude with respect to the machining position P. Anattitude of the head 5 is set in accordance with machining conditionssuch as a shape of a target and thus an irradiation direction of thelaser light 51 and a supply direction of the material (filler material)are appropriately controlled.

In an example of the attitude control mode illustrated in FIG. 4 , thewelding target portion (target line) Q has an annular shape in which itsurrounds a center position S. In other words, it is necessary toperform welding over the entire circumference of a circular ring. Whenthe first mechanism 2 is used, the head 5 moves along a circular route(path) surrounding a center position S in the XY plane (circling motion400). At that time, the rotational axis W of the head 5 also moves on acircular path “T”. When the second mechanism 3 is used, the head 5 canrotate 360° or more around the rotational axis W at any position on thecircular path (rotational motion 410). In other words, the head 5 canrotate 360° or more around the rotational axis W irrespective of theposition of the rotational axis W on the circular path T. Thus, anattitude (e.g., an orientation) of the head 5 with respect to the targetposition (i.e., machining position) P can be controlled. In other words,an irradiation direction of laser light and a supply direction of amaterial (filler material) with respect to a target are managed. Even inthe case of a large workpiece 10, an appropriate attitude of the head 5is maintained with respect to the machining position P of the workpiece(i.e., target) 10 along the entire circular path without moving theworkpiece 10. As a result, high quality and uniform welding is performedon the entire welding target portion Q. It should be noted that a targetline is not limited to an annular shape and can be, for example, aquadrangular shape or a wave shape. It is possible to perform laserwelding on components having any joining surfaces.

Referring again to FIG. 1A, in one embodiment, the second mechanism 3 issupported by the first mechanism 2 and includes a cavity unit (hollowunit) 30 connected to the head 5. In the embodiment, the cavity unit 30includes a rotating body (hollow shaft) 31, a supporting body 32, and amotor 33. The supporting body 32 is supported by the first mechanism 2.The rotating body 31 is rotatably supported by the supporting body 32.The head 5 is fixed to the rotating body 31. A driving force of themotor 33 is transmitted to the rotating body 31. The head 5 rotatesalong with the rotation of the rotating body 31. A rotational axis ofthe rotating body 31 coincides with the rotational axis W of the head 5.The rotation of the head 5 around the rotational axis W is guided viathe cavity unit 30. The cavity unit 30 can be configured such that adriving force of the motor 33 is transmitted to the rotating body 31 viaa transmission member such as a gear or a belt. Alternatively, thecavity unit 30 can include a hollow motor in which the rotating body 31,the supporting body 32, and the motor 33 are integrally combined. Inanother example, the cavity unit 30 can have a different constitutionfrom the above-described constitution.

The cavity unit 30 can have a cavity (insertion portion) 3 a provided atleast along the rotational axis W. As illustrated in a plurality ofexamples in FIG. 5 , the cavity unit 30 is provided on a first surface30 a which is a surface on a first side in a direction along therotational axis W (first end surface) and can have an opening 30 a 1connected to the cavity 3 a. The cavity unit 30 is provided on a secondsurface 30 b which is a surface on a second side in the direction alongthe rotational axis W (second end surface) and can have an opening 30 b1 connected to the cavity 3 a. In an embodiment, the cavity unit 30includes a tubular rotating body 31 and can be configured such that athrough hole as the cavity 3 a is provided in the rotating body 31. Inanother example, the cavity unit 30 can be configured such that thecavity 3 a is provided in a member having a shape other than a tubularshape. Alternatively and/or additionally, the cavity unit 30 can beconfigured to be divided into a plurality of members in an axialdirection. In the cavity unit 30, the plurality of separate members canbe configured to be able to move relative to each other.

As illustrated in FIG. 1A, parts of the optical cable 41 attached to thehead 5 and the material (filler material) 62 are arranged in the cavity3 a. When the optical cable 41 and the material 62 are arranged at leastalong the rotational axis W, the movement of the optical cable 41 andthe material 62 during the rotational motion of the head 5 is minimized.As a result, a load on the optical cable 41 and the material 62 duringan operation of the head 5 is reduced and damage or the like withrespect to the optical cable 41 and the material 62 is prevented.Furthermore, the cavity 3 a is advantageous in downsizing the entireapparatus. In addition, a laser welding apparatus 1 can be configuredsuch that part of the main body of the head 5 is arranged in the cavity3 a of the second mechanism 3 in addition to the optical cable 41 andthe material 62.

Here, examples of target objects to be machined to be applied to thelaser machining apparatus (laser welding apparatus) 1 include aworkpiece for manufacturing bearings such as a large roller bearing, anextra-large size roller bearing (an ultra-large roller bearing), or abearing for a rolling mill roll neck. Bearings manufactured using thelaser machining apparatus 1 can be provided in machines and vehicles.These machines can include machines (machinery) which use human powerfor power and machines which use power other than human power for power.Examples of machines include work machines, power generators, rollingmills, and the like. Furthermore, examples of vehicles includeautomobiles, railroad vehicles, large vehicles, construction machinevehicles, and the like. Examples of target objects to be machinedinclude a shaft for a wind power generator, a workpiece formanufacturing a member configured to support a gear, and the like.Alternatively, components other than those described above can be targetobjects to be machined. For example, the laser welding apparatus 1 canbe used not only for roller bearing cage pin welding but also for thegeneral vehicle component (automobile component) welding.

In an embodiment illustrated in FIG. 6 , an extra-large size rollerbearing (cylindrical roller bearing) is a workpiece to be machined. Theextra-large size roller bearing has a “roller” disposed between an innerring and an outer ring. An end portion of a pin 300 inserted into theroller is joined to a plate member (cage ring) 310. For this joining, awelding processing is performed on the target portion (circular targetline) Q over the entire circumference of the end portion of the pin 300.In another example, as a bearing, bearings of other types such astapered roller bearings and bearings other than roller bearings can beadopted.

In an embodiment of a tapered roller bearing, as illustrated in FIG. 7A,when metal active gas (MAG) welding is used, a filler is supplied overthe entire end portion of the pin 300 (welded portion 320). In thiscase, a sputter diameter is relatively large and a thermal effect isrelatively wide. As illustrated in FIG. 7B, when laser welding is used,it is easy to set a welding target portion to a necessary minimum, andfor example, only the surrounding of the end portion of the pin 300 canbe subjected to welding (welded portion 330). In other words, in anembodiment of a tapered roller bearing, the bearing illustrated in FIG.7B has an inner ring 250, an outer ring 260, a roller 270, the pin 300,and the cage ring (lateral plate) 310 and the welded portion 330 isprovided only around the end portion of the pin 300. In this case, thesputter diameter is very small and an amount is also relatively small.Thus, a thermal effect is relatively narrow. As a result, high qualityand uniform welding is performed over the entire target and a highquality product can be expected. Also in another example, high qualityand uniform welding is performed over the entire target on a bearing ora workpiece other than a bearing and a high quality product can beexpected.

An example associated with welding of a roller bearing will be describedbelow. As illustrated in FIG. 1A, in this example, a laser machiningapparatus is a laser welding apparatus 1 configured to perform laserwelding on a workpiece 10. The laser welding apparatus 1 includes ahollow structural moving mechanism 100 configured to move a laserwelding head 5 configured to irradiate the workpiece 10 with laserlight, a welding filler feeding mechanism 6 configured to supply awelding material 62 to a position on which laser welding is performed,and a welding unit 50 including the laser welding head 5 and the weldingfiller feeding mechanism 6 and including an insertion portion 3 athrough which an optical able 41 of the laser welding head 5 and a wirematerial 62 of the welding filler feeding mechanism 6 can be inserted.The hollow structural moving mechanism 100 includes a hollow shaft 31joined to the welding unit 50 and a motor 33 configured to rotate thehollow shaft 31. In an embodiment, the hollow structural movingmechanism 100 can include a hollow motor capable of rotating the weldingunit 50. The nozzle 61 is disposed to be inclined with respect to therotational axis W. The laser welding apparatus 1 includes a head axistilting mechanism (tilting mechanism) 4 having the laser welding head 5and the welding filler feeding mechanism 6 attached thereto such that itis inclined downward in a vertical direction for the purpose ofperforming laser welding on an object to be machined (workpiece ortarget), a hollow unit 30 having a rotational axis W configured torotate the head axis tilting mechanism 4, and an XYZ stage(three-dimensional actuator) 2 configured to rotate the rotating headaxis tilting mechanism 4 along a plane position of the workpiece 10 onwhich laser welding is performed. Alternatively, a unit in which atwo-dimensional actuator, a three-dimensional actuator and/or a uniaxialactuator are combined can be used instead of the XYZ stage. Drivecontrol for the XYZ stage 2, the hollow unit 30, the laser welding head5, and the welding filler feeding mechanism 6 is performed by thecontroller 110.

As illustrated in FIG. 1B, the XYZ stage 2 can move three-dimensionallyin XYZ directions and an X-direction linear motion mechanism 21 isattached to move in a plane in the XYZ stage 2 in a horizontal directionwhich is perpendicular to a vertical direction. A Y-direction linearmotion mechanism 22 is attached to move in a plane in the XYZ stage 2 ina horizontal direction which is perpendicular to a vertical direction ina direction different from an X direction.

The X-direction linear motion mechanism 21 and the Y-direction linearmotion mechanism 22 synchronously rotate with the rotational axis Wwhile being driven in two directions, that is, an X direction and a Ydirection in a plane, such that a center of the rotational axis W drawsa circle (refer to reference symbols 400 and 410 in FIG. 4 ) and thelaser welding head 5 is configured to always face a predetermineddirection with respect to a welded place of the work item 10. AZ-direction linear motion mechanism 23 is attached to move in the XYZstage 2 in the vertical direction. The Z-direction linear motionmechanism 23 is driven so that the focal point of the laser light 51 isaligned with a welded place of the workpiece 10 before welding isstarted to adjust a laser irradiation position from the laser weldinghead 5.

The head axis tilting mechanism 4 is a common integral supporting bodyincluding the laser welding head 5 and the welding filler feedingmechanism 6 configured to supply the welding material 62 and can bemoved in an arbitrary direction using a servomotor 33 configured torotatably drive the hollow unit 30. Furthermore, in order to preventreflected light from a surface of the workpiece from returning directlyto the laser welding head 5, the laser welding head 5 is attached suchthat a laser irradiation axis has a fixed angle (head axis inclinationangle) D2 with respect to an axial direction of the rotational axis W.

The hollow unit 30 (the hollow shaft 31) has a hollow and circular(annular) outer circumferential surface when viewed from the axialdirection of the rotational axis W and the plate-like head axis tiltingmechanism 4 included in the XYZ stage 2 and protruding from the lowerside of the outer circumferential surface is attached above the outercircumferential surface thereof. The hollow unit 30 includes a gearhaving a structure in which it turns along a circular outercircumferential (ring) surface in synchronization with the rotation ofthe head axis tilting mechanism 4 about the rotational axis W when theservomotor 33 is driven.

In this way, since the workpiece 10 is not rotated, the apparatus can beminiaturized. Furthermore, when the hollow unit 30 in which an axiscenter portion serving as the rotational axis W is the hollow insertionportion 3 a is used, it is possible to pass a welding filler wire 62, alaser transmission optical fiber cable 41, or the like through theinsertion portion 3 a. Thus, a burden is not exerted on a wire materialsuch as the welding filler wire 62 and the laser transmission opticalfiber cable 41 even when the laser welding head 5 rotates 360° as incircular welding. Therefore, it is possible to prevent a wiring such asthe laser transmission optical fiber cable 41 from being twisted anddamaged. Furthermore, when disposing the laser welding head 5 at adistance from the workpiece 10, it is possible to insert a part of thehead 5 into the insertion portion 3 a serving as a hollow portion in thehollow unit 30 (refer to FIG. 4 ).

The laser welding head 5 has a rod shape in which it protrudes downwardin the axial direction of the rotational axis W and is attached to beable to change an angle thereof with respect to the rotational axis Wusing the head axis tilting mechanism 4. A laser beam is transmitted tothe laser welding head 5 via the laser transmission optical fiber cable41 from a laser oscillation apparatus (not shown). Furthermore, aplurality of lenses as an optical system configured to converge thelaser light 51 up to an intensity necessary for laser welding aredisposed in the laser welding head 5. Thus, the laser welding head 5radiates energy (laser light) in a state in which the converged laserlight 51 is condensed on the workpiece 10 as a heat source. A beam spotof the laser light 51 is radiated with a very small diameter (forexample, a diameter of about several hundred μm or less) with highpositional accuracy. It is possible to prevent the laser transmissionoptical fiber cable 41 from being twisted and damaged when a rotationalcoupling is provided to a coupling portion between the lasertransmission optical fiber cable 41 and the laser welding head 5.

The welding filler feeding mechanism 6 has a downward and inclinedattitude together with the head axis tilting mechanism 4 and the laserwelding head 5 and is movably attached using the attachment plate 63. Inthe embodiment, the planar movement in the X axis direction and the Yaxis direction is synchronized with the rotation of the W axis so thatthe head axis inclination angle D2 and a feed attitude of the weldingfiller feeding mechanism 6 are maintained in a predetermined attitudeduring welding and driving is performed so that an irradiation directionof the laser light 51 and a feeding direction of the welding fillerfeeding mechanism 6 are upheld in a predetermined manner with respect toa traveling direction of the laser welding head 5 (refer to FIG. 4 ).Furthermore, the welding filler is fed in accordance with a weldingspeed.

As a welding material fed by the welding filler feeding mechanism 6, thewelding filler wire 62 which is generally fed in feeding a wire is used.The welding filler nozzle 61 configured to set a position to which thewelding filler wire 62 is fed is provided in the welding filler feedingmechanism 6.

The laser welding method according to the embodiment performs laserwelding on the workpiece 10 in an annular shape through operations ofthe head axis tilting mechanism 4 having the laser welding head 5 andthe welding filler feeding mechanism 6 attached thereto to be inclineddownwardly in the vertical direction, the hollow unit 30 having therotational axis W configured to rotate the head axis tilting mechanism4, and the XYZ stage 2 configured to rotate the rotating head axistilting mechanism 4 along the plane position of the workpiece 10 onwhich the laser welding is performed. Drive control for the XYZ stage 2,the hollow unit 30, the laser welding head 5, and the welding fillerfeeding mechanism 6 is performed by the controller 110.

The above-described laser welding method using the laser weldingapparatus 1 will be described below with reference to the schematicdiagram in FIG. 4 .

Before welding

-   -   (1) The workpiece 10 is fixed to a placing table. In the        embodiment, the workpiece 10 to be welded is a metallic member        and a plurality of annular welded places Q serving as portions        on which welding is performed are present on an upper end        surface of the workpiece 10 in the axial direction (refer FIGS.        6 and 7B). Examples of such a member include a cage or the like        used for a roller bearing. A roller bearing cage of a welding        pin type is constituted of a pin configured to pass through a        hollow roller and upper and lower cage rings configured to hold        the pin, one of the cage rings and a pin end portion are fixed        using a screw or the like and the other cage ring is joined        through welding.    -   (2) The laser welding apparatus 1 having the laser welding head        5 and the welding filler feeding mechanism 6 mounted therein is        set in the XYZ stage 2 having the X-Y-(plane)-direction linear        motion (movement) mechanisms 21 and 22 and the rotational        axis W. At that time, in order to prevent the occurrence of        interference or twisting, the laser transmission optical fiber        cable 41, the welding filler wire 62, and the like are caused to        pass through the insertion portion 3 a serving as the hollow        portion in the hollow unit 30.    -   (3) In order to perform setting so that the laser welding head        faces a predetermined direction with respect to the machining        position (welding position) P of the workpiece 10 by adjusting        the X-direction linear motion mechanism 21 and the Y-direction        linear motion mechanism 22 and to prevent reflected light from        the surface of the workpiece from returning directly to the        laser welding head 5, the laser welding head 5 is attached so        that the laser irradiation axis has the fixed angle (head axis        inclination angle) D2 with respect to the axial direction of the        rotational axis W. Examples of the head axis inclination angle        D2 include about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45,        50, 60, 70, or 80°. The above-described value is an example of a        typical numerical value and an inclination angle is not limited        to the above-described values.    -   (4) A position of the laser welding head 5 is adjusted in        advance so that the focal point of the laser light 51 is aligned        with a welding target portion of the workpiece 10 by driving the        Z-direction linear motion mechanism 23. In addition, the welding        filler feeding mechanism 6 and a distal end position and a        direction of the filler nozzle 61 are adjusted so that the        welding filler wire 62 is appropriately fed to the machining        position P.        During welding    -   (1) When the welding operation is started, as illustrated in        FIG. 4 , the controller 110 causes the X-Y-direction linear        motion mechanisms 21 and 22 and the hollow shaft 3 in the XYZ        stage 2 to operate so that the machining position P traces a        preset welding shape (a circle Q which is a circle having a        radius R in an upper end surface of the workpiece 10 in the        embodiment) while a direction of the laser welding head 5 is        upheld in a predetermined matter with respect to the machining        position P.    -   (2) To be specific, the X-direction linear motion mechanism 21        and the Y-direction linear motion mechanism 22 are synchronously        driven so that the center of the rotational axis W draws a        circle in an X-Y planar shape and the rotational axis W is        caused to be synchronously rotated. In other words, the movement        trajectory of the W axis using the XYZ stage 2 (a circle of a        broken line in FIG. 4 ) and the rotation of the laser welding        head 5 indicated by a circle of a solid line moving on the        broken line in FIG. 4 are synchronized. Thus, the machining        position P moves on the circle Q while the direction of the        laser welding head 5 is kept fixed in a predetermined manner        with respect to the machining position P.    -   (3) Since the head axis inclination angle D2 and the attitude of        the welding filler feeding mechanism 6 are always kept in a        predetermined attitude during welding, the reflected light of        the laser light 51 does not reach the laser welding head 5.        Furthermore, it is possible to perform laser welding with a        rotation angle of 360° or more with respect to the workpiece 10        because the welding filler wire 62 is continuously fed to the        machining position P appropriately.

EXPLANATION OF NUMERALS AND CHARACTERS

-   -   1 Laser welding apparatus (laser machining apparatus)    -   2 XYZ stage (XY stage)    -   4 Head axis tilting mechanism    -   5 Laser welding head    -   6 Welding filler feeding mechanism    -   10 Work item (workpiece)    -   100 Hollow structural moving mechanism

The invention claimed is:
 1. A laser machining apparatus comprising: ahead having an optical outlet from which laser light is output; anoptical cable attached to the head; a nozzle attached to the head todirect a material supplied to a target; and a moving mechanism having adriving portion; wherein the moving mechanism includes a first mechanismconfigured to allow the head to move in a curved manner in at least atwo-dimensional plane and a second mechanism, which has a rotationalaxis and a cavity unit that has a cavity provided along the rotationalaxis, to allow the head to rotate 360° or more around the rotationalaxis along with the optical cable and the material, a tilting mechanismis arranged between the cavity unit and the head, the tilting mechanismis attached to the cavity unit and is configured to change an angle ofthe head with respect to the rotational axis, and a controller has anattitude control mode in which the moving mechanism is controlled sothat the head rotates around the rotational axis while the head moves inthe curved manner in at least the two-dimensional plane.
 2. The lasermachining apparatus according to claim 1, wherein the cavity unit issupported by the first mechanism and joined to the head, and the opticalcable and the material are arranged through the cavity of the cavityunit.
 3. The laser machining apparatus according to claim 1, wherein thehead and the nozzle are disposed to be inclined with respect to therotational axis.
 4. The laser machining apparatus according to claim 1,wherein, in the attitude control mode, the moving mechanism iscontrolled so that a location of at least one of the optical outlet ofthe head and a distal end of the nozzle is upheld in front of amachining position while the head moves in the curved manner in at leastthe two-dimensional plane.
 5. The laser machining apparatus according toclaim 1, wherein, in the attitude control mode, the moving mechanism iscontrolled so that an irradiation direction of the laser light is in atangential direction of a curved line of a curved machining target.
 6. Alaser welding apparatus which performs laser welding on a workpiece,comprising: a laser welding head configured to irradiate the workpiecewith laser light; an optical cable attached to the laser welding head; awelding filler feeding mechanism attached to the laser welding head, andconfigured to supply a welding material to a position on which the laserwelding is performed; a hollow structural moving mechanism configured tomove a welding unit including the laser welding head and the weldingfiller feeding mechanism, the hollow structural moving mechanismcomprising a cavity unit defining a rotational axis and including acavity, the cavity being provided along the rotational axis and throughwhich an optical cable of the laser welding head and a wire material ofthe welding filler feeding mechanism are inserted; and a tiltingmechanism arranged between the cavity unit and the laser welding head,the tilting mechanism being attached to the cavity unit and beingconfigured to change an angle of the laser welding head with respect tothe rotational axis, wherein, in a state in which the optical cable ofthe laser welding head and the wiring material of the welding fillerfeeding mechanism are inserted through the insertion portion the cavityof the hollow structural moving mechanism, the laser welding head isallowed to rotate 360° or more around the rotational axis.
 7. The laserwelding apparatus according to claim 6, wherein the hollow structuralmoving mechanism includes a hollow shaft that is joined to the weldingunit and a motor configured to rotate the hollow shaft.
 8. The laserwelding apparatus according to claim 6, wherein the hollow structuralmoving mechanism includes a hollow motor capable of rotating the weldingunit.
 9. The laser welding apparatus according to claim 6, comprising: atwo-dimensional actuator configured to move the welding unit and thehollow structural moving mechanism.
 10. The laser welding apparatusaccording to claim 6, comprising: a three-dimensional actuatorconfigured to move the welding unit and the hollow structural movingmechanism.
 11. The laser welding apparatus according to claim 6, whereinthe tilting mechanism is configured to allow the laser welding head tobe attached to be inclined with respect to a vertical direction.
 12. Thelaser welding apparatus according to claim 6, wherein a rotationalcoupling is provided at a coupling portion between the laser weldinghead and a laser transmission optical fiber cable serving as the wirematerial of the laser welding head.
 13. The laser welding apparatusaccording to claim 6, further comprising: a controller having anattitude control mode in which the hollow structural moving mechanism iscontrolled so that the laser welding head rotates around the rotationalaxis while the laser welding head moves in a curved manner in at least atwo-dimensional plane.
 14. A laser welding method using the laserwelding apparatus of claim 6, wherein the hollow structural movingmechanism and a two-dimensional actuator are synchronously driven sothat an irradiation direction of laser light of the laser welding headand a feeding direction of the welding filler of the welding fillerfeeding mechanism are upheld in a predetermined manner with respect to atraveling direction of the laser welding head.